A 39-year-old building materials supplier was shot dead in Birati, around 18km north of Calcutta, when he was walking home from a club near Banik More on Wednesday night.

Witnesses have told the police that the attackers came riding two motorcycles from behind and pumped five bullets into Subhrajit Dutta around 10.30pm.

Alarmed at the sound of firing, some residents alerted police. He was taken to hospital, where he was declared dead.

Hundreds of residents took to the streets in Birati on Wednesday night demanding the arrest of the assassins. A large police contingent led by officers of the Barrackpore police commissionerate and Nimta police station persuaded the residents to withdraw their protest.

On Thursday, a police picket was set up in the locality, which has witnessed a spurt in construction of housing complexes in recent years. The police have started scanning CCTV footage and a case of murder against unknown persons has been drawn up at Nimta police station.

Subhrajit’s murder came within hours of an attack on Babulal Singh, alleged to be a strongman and a member of the syndicate that controls supply of building materials in Birati, by a group of youths.

Investigators said Babulal was once Subhrajit’s associate in the business of supplying construction materials and had borrowed around Rs 4 lakh from the latter several years back.

Babulal had reportedly told Subhrajit that the amount would be invested in expanding their business and constructing an office for the duo in Birati.

For some time Subhrajit allegedly started demanding the money back from Babulal. On Wednesday afternoon, a group of youths attacked Babulal with marble tiles.

He was hit on his head with a tile and left to bleed till some associates rescued him. He was later admitted to a private hospital on EM Bypass.

“It is still too early to conclude that Subhrajit’s murder was the fallout of the attack on Babulal but we are not ruling out the possibility,” said a senior officer of the Barrackpore police commissionerate.

“We are tracing Babulal’s antecedence. The assassins will be arrested shortly,” the officer said.